An autopsy case of aggressive CD30+ extra-nodal NK/T-cell lymphoma initially manifested with granulomatous myositis.

This study reports an autopsy case of a 53 year-old male with rapidly progressive extra-nodal NK/T-cell lymphoma accompanied with unusual clinical and pathologic features. He was initially presented with localized swelling and tenderness in the right lower extremity and the biopsy from the calf muscle was interpreted as granulomatous myositis masquerizing lymphoma. The biopsy from erythematous skin lesion of trunk showed infiltration of medium sized atypical lymphoid cells with relatively plump cytoplasm and immunophenotype of CD30+, CD56+/- and surface CD3-, which lead to the diagnosis of CD30+ anaplastic large cell lymphoma. About 2 months later, nasal obstruction was developed and the nasal biopsy was done. After confirmation of EBV infection, he was finally diagnosed as extra-nodal NK/T-cell lymphoma with peculiar immunophenotype of CD3 dim+ and CD30+. Despite the chemotherapy, he was going rapidly downhill and died of respiratory and multi-organ failure 8 months after the onset of soft tissue lesion. At autopsy, disseminated angiocentric lymphoma was found all over the internal organs including the brain. This case emphasizes that extra-nodal NK/T-cell lymphoma should be considered as a cause of granulomatous myositis and can express CD30 positivity and CD3 weak positivity, which are unusual but rarely predominant feature of NK/T-cell lymphoma.